Preheat the oven to 375°F. Grease a 2-quart baking dish.
Place the potatoes in a large pot and cover with cold water. Bring to a boil and cook for 12–15 minutes, until fork-tender. Drain well.
Add the butter, sour cream, half and half, cream cheese, garlic powder, salt, and pepper. Mash until creamy.
Stir in half of the shredded cheddar cheese, bacon, and chives, if using.
Spread the potatoes into the prepared baking dish. Sprinkle the remaining cheddar and bacon over the top.
Bake uncovered for 20–25 minutes, until hot and lightly golden.
Garnish with the remaining chopped chives, if desired, and serve warm.
Notes
Consistency: For smoother mashed potatoes, peel the potatoes. You can also run them through a potato ricer. We like our mashed potatoes a little chunky.